Orbits

These flashcards cover key terms and concepts related to the anatomy and functions of the orbit, as well as clinical conditions associated with it.

Orbit

A pyramidal structure that houses the eyeball and associated structures.

Bony boundaries

The seven bones that form the orbit: frontal, sphenoid, maxilla, zygomatic, palatine, lacrimal, and ethmoid.

Foramina

Openings in the bony boundaries of the orbit allowing passage for nerves and blood vessels.

Frontal bone

The large bone forming the forehead; part of the orbit.

Zygomatic bone

The bone that forms the prominence of the cheek; contributes to the orbit.

Maxilla

The upper jawbone, which forms part of the orbit.

Lacrimal bone

A small bone forming part of the front part of the medial wall of the orbit.

Ethmoid bone

A small bone located between the eyes that contributes to the orbit.

Optic canal

An opening in the sphenoid bone that transmits the optic nerve and ophthalmic artery.

Superior orbital fissure

A slit-like opening between the greater and lesser wings of the sphenoid bone for nerve and vessel passage.

Exophthalmos

Protrusion of the eyeball, often due to inflammation or tumors.

Ciliary muscles

Muscles that control the shape of the lens for focusing.

Conjunctiva

A mucous membrane covering the front of the eye and lining the eyelids.

Tear drainage system

The system responsible for draining tears from the eye via the punctum and lacrimal sac.

Levator palpebrae superioris

A muscle that elevates the upper eyelid.

Oculomotor nerve (CN III)

The cranial nerve responsible for most eye movements and controlling pupil size.

Trochlear nerve (CN IV)

The cranial nerve that innervates the superior oblique muscle for eye movement.

Abducens nerve (CN VI)

The cranial nerve controlling the lateral rectus muscle, allowing lateral eye movement.

Trigeminal nerve (CN V)

The cranial nerve providing sensory information from the face and motor functions for chewing.

Optic nerve (CN II)

The nerve that transmits visual information from the retina to the brain.

Ophthalmic artery

The artery supplying blood to the orbit and its contents.

Superior ophthalmic vein

A vein that drains blood from the orbit to the cavernous sinus.

Inferior ophthalmic vein

A vein that drains blood from the orbit and connects with the pterygoid plexus.

Central retinal artery

An artery that supplies blood to the retina and runs within the optic nerve.

Choroidal blood supply

The blood supply to the outer retinal layers, supported by branches of the ophthalmic artery.

Horner’s syndrome

A condition that presents with ptosis, miosis, and anhidrosis due to sympathetic nerve disruption.

Partial ptosis

Drooping of the upper eyelid resulting from nerve damage.

Miosis

Constricted pupil, often associated with sympathetic nerve damage.

Anhidrosis

Absence of sweating, particularly on one side of the face, due to sympathetic disruption.

Autonomic functions

Involuntary functions of the eye, including tear production and pupil dilation.

Anterior ethmoidal nerve

A branch of the nasociliary nerve that provides sensory innervation to the sinonasal cavity.

Lacrimal nerve

A branch of the ophthalmic nerve that supplies sensory fibers to the lacrimal gland and skin.

Ciliary ganglion

A relay center for parasympathetic innervation to the eye, associated with CN III.

Pupil size

Controlled by the iris muscle in response to light levels.

Lens control

Managed by ciliary muscles for focusing vision.

Lacrimal gland

Produces tears and is innervated by parasympathetic fibers from CN VII.

Gray's Anatomy

A comprehensive reference for anatomical structures and relationships in the body.

Clinical significance of blood supply

Understanding the vascular arrangements and implications for conditions like CRAO.

Marginal reflex

The tear maintenance mechanism involving the lacrimal gland and puncta.

Muscles of eyelid

Muscles that control eyelid movements, including the levator palpebrae and orbicularis oculi.

Clinical testing of eye movements

Assessing muscle function and coordination during various gaze directions.

Eyelids

Protective structures that cover the eyeball, contributing to tear drainage.

Tarsal plate

A connective tissue structure that helps maintain the shape of the eyelid.

Autoimmune conditions

Diseases where the immune system attacks the body's own tissues, relevant in cases of exophthalmos.

Medial rectus

An extraocular muscle responsible for adduction of the eye.

Eye movement rules

Guidelines for understanding how extraocular muscles move the eye.

Clinical images

Visual references used to illustrate clinical cases related to eye anatomy.

Sphenoid bone

A bone at the base of the skull involved in forming the orbit.

Annulus of Zinn

The tendinous ring at the apex of the orbit, where extraocular muscles originate.

Optic disc

The point of exit for the optic nerve from the eye, where blood supply is critical.

Atrophied sweating

Decreased or absent sweating in a region, often linked to nerve damage.

Visually isolated testing

Assessing the function of eye muscles in a position that isolates their action.

Cranial nerve pathways

Neural pathways related to the cranial nerves that innervate ocular structures.

Pancoast tumour

A type of lung cancer that can cause Horner’s syndrome if it compresses the sympathetic trunk.